A phosphor, a long-lived room temperature phosphorescent material for photo-driven phosphorescence growth and its application

Abstract

The present invention discloses a phosphor, a long-lifetime room-temperature phosphorescent material driven by light for phosphorescence growth and its application. The phosphor is a unique functional molecule driven by photoexcitation, which is beneficial to extending the long afterglow lifetime of the phosphorescent material. At the same time, using the copolymer of vinyl alcohol and ethylene (PVA-co-PE) as the polymer matrix, the phosphor with a biphenyl structure is doped to prepare the world's first long-lifetime room-temperature phosphorescent material in which the phosphorescence growth can be directly observed by light driving; this phosphorescent system allows the visualization of phosphorescence growth and the self-recovery of long-lifetime room-temperature phosphorescent behavior in the atmospheric environment. The visualization of phosphorescence growth enables efficient and rapid information transmission and destruction.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic room-temperature phosphorescent materials, and particularly relates to a phosphor, a long-life room-temperature phosphorescent material with photo-driven phosphorescence growth, and a preparation method and application thereof. Background Art

[0002] Phosphorescent materials are materials that can emit phosphorescence under the excitation of electromagnetic radiation and ionizing rays. Among them, pure organic room-temperature phosphorescent materials have attracted great attention due to their advantages such as low cost, good biocompatibility, and easy structural modification. These unique advantages enable them to be applied in many fields such as organic light-emitting diodes, bioimaging, information encryption, and anti-counterfeiting. However, the weak spin-orbit coupling and fast non-radiative decay of triplet excitons lead to low-efficiency intersystem crossing (ISC), making it difficult to achieve long-life phosphorescence emission. Generally speaking, achieving long-life phosphorescence emission can start from the following two processes: (1) improving the intersystem crossing (ISC) efficiency from the lowest excited singlet state (S1) to the excited triplet state (T n ) and from the lowest excited triplet state (T1) to the ground state (S0). This can be effectively achieved by enhancing the spin-orbit coupling or reducing the energy gap between the singlet and triplet states. (2) Suppressing the non-radiative transition process from the lowest excited triplet state to the ground state. However, due to the intense molecular thermal motion (vibration, collision, diffusion motion, etc.) and the quenching effect of oxygen, it is difficult to observe the organic phosphorescence phenomenon at room temperature.

[0003] In recent years, domestic and foreign research scholars have developed a series of highly efficient organic long-afterglow materials by using strategies such as crystal engineering, constructing host-guest systems to form hydrogen bond networks, polymer matrix doping, and aggregation-induced emission. Among them, the host-guest doped materials with PVA as the polymer matrix have occupied a place. They combine with the phosphor through a large number of hydrogen bonds of their own, thus showing good phosphorescent properties. However, using PVA as the polymer matrix, the emitted phosphorescence is easily quenched by water and oxygen in the air, and it is difficult to maintain the phosphorescence emission for a long time in the atmospheric environment. In addition, the existing phosphorescent materials cannot observe the phenomenon of phosphorescence growth with the naked eye and need to rely on instruments to achieve observation, making it difficult to achieve efficient and rapid information transmission and destruction. Summary of the Invention

[0004] Aiming at the above deficiencies existing in the prior art, the purpose of the present invention is to provide a phosphor with a long afterglow life and a long-life room-temperature phosphorescent material with photo-driven phosphorescence growth, so as to solve the technical problems that the existing phosphorescent materials cannot observe the phenomenon of phosphorescence growth with the naked eye, it is difficult to achieve efficient and rapid information transmission and destruction, and it is difficult to maintain the phosphorescence emission for a long time in the atmospheric environment.

[0005] Furthermore, a preparation method and application of the long-life room-temperature phosphorescent material are also provided.

[0006] To solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0007] The present invention provides a phosphor, the structure of which is shown in formula (1):

[0008]

[0009] Among them, the structure of R is shown in formula (2):

[0010]

[0011] Furthermore, the preparation process route of the phosphor is as follows:

[0012]

[0013] Furthermore, the preparation process method of the phosphor includes:

[0014] 1) After dissolving 4'-hydroxy-[1,1'-biphenyl]-4-carbaldehyde in tetrahydrofuran, potassium carbonate is added, and the mixture is stirred evenly for 0.5 h under an inert atmosphere at 65 °C;

[0015] 2) Dissolve hexachlorocyclotriphosphazene in tetrahydrofuran;

[0016] 3) The solution obtained in step 2) is added dropwise to the solution obtained in step 1), and after reacting fully at 70 °C for 12 h, it is cooled to room temperature, and tetrahydrofuran is removed. The pale yellow product obtained after purification of the residue is the phosphor.

[0017] Among them, the molar ratio of 4'-hydroxy-[1,1'-biphenyl]-4-carbaldehyde to hexachlorocyclotriphosphazene is 6:1.

[0018] The present invention also provides a long-lived room-temperature phosphorescent material for light-driven phosphorescence growth, including the above-mentioned phosphor. Its preparation method includes:

[0019] Mix the phosphor and the polymer matrix in a ratio of (0.1 - 3) mg: 1 ml, stir evenly, and then drop the obtained mixed solution on a glass slide to form a transparent film, thus obtaining the long-lived room-temperature phosphorescent material; among them, the polymer matrix is a dimethyl sulfoxide solution of poly(vinyl alcohol-co-ethylene). The mass percentage of ethylene in the poly(vinyl alcohol-co-ethylene) is 27 - 38%.

[0020] The present invention also provides the application of the long-lived room-temperature phosphorescent material, using the long-lived room-temperature phosphorescent material in the fields of information transmission and destruction, and dynamic green anti-counterfeiting.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The phosphor provided by the present invention contains biphenyl groups. Different conformations are generated by the free rotation between benzene rings, which is conducive to the stacking between molecules. In addition, the biphenyl structure can form strong intermolecular π-π interactions, which is also conducive to the formation of stacking of molecules in the polymer matrix. The stacked molecular clusters can enhance the intersystem crossing and spin-orbit coupling between molecules, thereby prolonging the long afterglow lifetime.

[0023] 2. The present invention uses a copolymer of vinyl alcohol and ethylene (PVA-co-PE) as the polymer matrix, and dopes the phosphor with a biphenyl structure to prepare the world's first long-life room-temperature phosphorescent material that can directly observe the growth of phosphorescence by light driving. The long-life room-temperature phosphorescent material prepared by the present invention has ultraviolet-stimulated response behavior. By irradiating with an ultraviolet lamp, the interaction between small molecules and polymers is adjusted. It can be clearly observed that the long-life phosphorescence grows from scratch after a short irradiation time, and the phosphorescence intensity, phosphorescence lifetime, luminescence brightness and other properties of the material after irradiation have been qualitatively improved. After removing the ultraviolet light and placing the film in the atmospheric environment, the long-life phosphorescence will disappear after a period of time. By heating, the process of the disappearance of the long-life phosphorescence can be accelerated, that is, dynamic cycling can be realized. It has important value for the development of artificial molecular switches with visual control of confidential information transmission and destruction.

[0024] 3. The present invention functionalizes a general small molecule chromophore and then physically dopes it with a polymer matrix to prepare a transparent film. Under the short-time irradiation of a 254 nm ultraviolet lamp, the growth of white stripes can be observed on the transparent film, so as to directly observe the phenomenon of phosphorescence growth with the naked eye, without the need to observe with the aid of instruments, which is easy to realize efficient and rapid information transmission and destruction, and is of great significance for information transmission and confidentiality. After turning off the excitation light source, bright blue-green afterglow can be generated, and the afterglow duration is up to 10 s.

[0025] 4. The composition of the long-life room-temperature phosphorescent material of the present invention is simple. Different from inorganic phosphorescent materials, it does not require rare elements, and the cost is greatly reduced. Moreover, the present invention overcomes the deficiencies of difficult preparation, large brittleness, poor stability of crystal materials and long preparation time of polymer long afterglow materials, and minimizes possible side reactions at the same time. Description of the Drawings

[0026] Figure 1 is the 1H NMR spectrum of the phosphor THBE before irradiation;

[0027] Figure 2 is the 1H NMR spectrum of the phosphor THBE after irradiation with a 254 nm ultraviolet lamp for 1 minute;

[0028] Figure 3Infrared spectra of the pale yellow products obtained in Example 1, Example 2, and Example 3;

[0029] Figure 4 Figure showing the phosphorescence growth phenomenon of the film obtained in Example 1 under excitation by a 254 nm ultraviolet lamp in a room-temperature atmospheric environment;

[0030] Figure 5 Cyclic experiment of the film obtained in Example 1 under excitation by a 254 nm ultraviolet lamp in a room-temperature atmospheric environment;

[0031] Figure 6 Phosphorescence spectra of the film obtained in Example 1 before and after irradiation with a 254 nm ultraviolet lamp for 1 minute in a room-temperature atmospheric environment;

[0032] Figure 7 Phosphorescence lifetime decay curves of the film obtained in Example 1 before and after irradiation with a 254 nm ultraviolet lamp for 1 minute in a room-temperature atmospheric environment;

[0033] Figure 8 Phosphorescence photograph of the film obtained in Example 1 after irradiation with a 254 nm ultraviolet lamp for 1 minute in a room-temperature atmospheric environment;

[0034] Figure 9 Phosphorescence emission spectra and phosphorescence lifetime decay curves of the film obtained in Example 2 before and after irradiation with a 254 nm ultraviolet lamp for 1 minute in a room-temperature atmospheric environment;

[0035] Figure 10 Phosphorescence emission spectra and phosphorescence lifetime decay curves of the film obtained in Example 3 before and after irradiation with a 254 nm ultraviolet lamp for 1 minute in a room-temperature atmospheric environment;

[0036] Figure 11 Phosphorescence photographs of the films obtained in Example 2 and Example 3 after irradiation with a 254 nm ultraviolet lamp for 1 minute in a room-temperature atmospheric environment. Detailed implementation manners

[0037] The following further describes in detail the specific implementation manners of the present invention in conjunction with specific examples.

[0038] The numerical ranges in the present invention should be understood to specifically disclose each intermediate value between the upper and lower limits of the range. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0039] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Although this invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of this invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the said documents. In case of conflict with any incorporated document, the content of this specification shall prevail. Regarding the use of "comprising", "including", "having", "containing", etc. herein, they are all open-ended terms, meaning including but not limited to.

[0040] Unless otherwise specified, the experimental methods used in this invention are all conventional methods.

[0041] The materials, reagents, etc. used in this invention, unless otherwise specified, can all be obtained by purchase or synthesized by known methods.

[0042] In the quantitative tests of this invention, three repeated experiments are set, and the results are averaged.

[0043] I. This invention provides a THBE-functionalized phosphor, and its structural formula is as follows:

[0044]

[0045] Furthermore, a preparation method of the above phosphor is also provided, and its process route is as follows:

[0046]

[0047] The specific steps include:

[0048] 1) After dissolving 4'-hydroxy-[1,1'-biphenyl]-4-carbaldehyde in tetrahydrofuran, potassium carbonate is added, and it is stirred evenly for 0.5 h under an inert atmosphere at 65 °C;

[0049] 2) Dissolve hexachlorocyclotriphosphazene in tetrahydrofuran;

[0050] 3) The solution obtained in step 2) is added dropwise to the solution obtained in step 1), and after reacting fully at 70 °C for 12 h, it is cooled to room temperature, and tetrahydrofuran is removed. The pale yellow product obtained after purification of the residue is the phosphor.

[0051] II. This invention also provides a long-lived room-temperature phosphorescent material for photo-driven phosphorescence growth containing the above phosphor, and its preparation method is:

[0052]

[0053] Among them, the concentration of the polymer solution is 30 mg / mL, and the functionalized phosphor, polyvinyl alcohol (PVA), and poly(vinyl alcohol-co-ethylene) are all prepared into doping solutions with a concentration of 1 mg / mL, and THBE@PVA films, THBE@PVA27PE films, THBE@PVA32PE films, and THBE@PVA38PE films are prepared.

[0054] Mix the phosphor with a dimethyl sulfoxide solution of poly(vinyl alcohol-co-ethylene), stir evenly, and then drop the obtained mixed solution on a template to make a transparent film, that is, a long-lived room-temperature phosphorescent material is obtained.

[0055] III. Application research of long-lived room-temperature phosphorescent materials

[0056] Under different substrates, irradiate the prepared transparent film with ultraviolet light. After removing the excitation light source, it is found that the transparent film with PVA as the substrate does not produce white stripes and has no afterglow. The transparent film with poly(vinyl alcohol-co-ethylene) as the substrate is covered with white stripes and has an obvious afterglow phenomenon. After green printing on this film and heating at 90 °C for 1 min, the printed information disappears and new information can be printed again. It is proved that the transparent film is a long-lived room-temperature phosphorescent material that can drive phosphorescence growth by ultraviolet light, and has the application function of an artificial molecular switch for visually controlling the transmission and destruction of confidential information in a green and environmentally friendly manner.

[0057] IV. Examples

[0058] Example 1

[0059] A preparation method of a long-lived room-temperature phosphorescent material (a host-guest doped long afterglow material) that drives phosphorescence growth by light includes the following steps:

[0060] (1) Synthesis of THBE-functionalized phosphor

[0061] Dissolve 4'-hydroxy-[1,1'-biphenyl]-4-carbaldehyde (1 g, 0.005 moL) in tetrahydrofuran (THF) (50 mL), and then add K2CO3 (1.1056 g, 0.008 mol); then stir the solution for 30 minutes under the protection of an inert gas (such as argon) at 65 °C to obtain solution A; subsequently, dissolve chlorotriphosphazene (0.2897 g, 0.0008 mol) in THF (5 mL) to obtain solution B, and drop solution B into solution A drop by drop, and react for 12 hours; then cool the reaction mixture to room temperature and use a rotary evaporator to remove the excess THF; dissolve the obtained residue in dichloromethane, extract it five times with deionized water, dry the obtained organic layer with anhydrous MgSO4 and filter, remove the filtrate from dichloromethane with a rotary evaporator, and dry it in an oven to finally obtain a pale yellow product.

[0062] Figure 1 And Figure 2 are the 1H NMR spectra of the pale yellow products before and after UV lamp irradiation. From Figure 1 and Figure 2 it can be seen that there are two sets of signals in the figure, and the integral intensity ratio is 1:8, which is consistent with the structure of the THBE-functionalized phosphor small molecule, and the chemical shifts of each group are also in line, indicating that the synthesized yellow powder product is the expected product.

[0063] Figure 3 is the infrared spectrum of the pale yellow product. From Figure 3 it can be seen that the stretching vibration peaks of C-H on the aldehyde group are at 2918 cm -1 and 2850 cm -1 , and the characteristic peak of the benzene ring is at 839 cm -1 , indicating that the THBE-functionalized phosphor has been successfully synthesized.

[0064] In summary, through the detection of 1H NMR ( Figure 1 , Figure 2 ) and infrared spectrum ( Figure 3 ), the obtained yellow powder product has the following structure:

[0065]

[0066] This proves that the THBE-functionalized phosphor has been successfully synthesized in this invention.

[0067] (2) Long-lived room temperature phosphorescent materials for light-driven phosphorescence growth

[0068]

[0069] Among them, the concentration of the polymer solution is 30 mg / mL, and the functionalized phosphor, polyvinyl alcohol (PVA), and poly(vinyl alcohol-co-ethylene) are all prepared into doped solutions with a concentration of 1 mg / mL, and THBE@PVA films, THBE@PVA27PE films, THBE@PVA32PE films, and THBE@PVA38PE films are prepared.

[0070] The phosphor THBE (1 mg / mL) was respectively dispersed in PVA-co-27%PE with a concentration of 30 mg / mL. A homogeneous solution was obtained by ultrasonic treatment for 1 minute. The prepared homogeneous solution was dropped onto a 75 mm×25 mm glass substrate and then heated on a hot plate at 100 °C for 15 min to obtain a transparent film.

[0071] Example 2

[0072] This example provides a method for preparing a long-lifetime room-temperature phosphorescent material with light-driven phosphorescence growth. The main steps are the same as those in Example 1, except that PVA-co-32%PE is used instead of PVA-co-27%PE.

[0073] Example 3

[0074] This example provides a method for preparing a long-lifetime room-temperature phosphorescent material with light-driven phosphorescence growth. The main steps are the same as those in Example 1, except that PVA-co-38%PE is used instead of PVA-co-27%PE.

[0075] Comparative Example

[0076] This comparative example provides a method for preparing a room-temperature phosphorescent material. The main steps are the same as those in Example 1, except that PVA is used instead of PVA-co-27%PE.

[0077] The obtained thin film of the comparative example was irradiated with ultraviolet light. After removing the excitation light source, the transparent thin film with PVA as the matrix did not produce white stripes and had no afterglow.

[0078] V. Effect Analysis

[0079] The thin films prepared with different polymer matrices in Examples 1-3 were irradiated with ultraviolet light. Different afterglow phenomena could be observed after removing the excitation light source.

[0080] Under the room-temperature atmospheric environment, the thin film obtained in Example 1 was irradiated with a 254 nm ultraviolet lamp for 1 minute. During the irradiation process, the change in the phosphorescence intensity of the thin film was as Figure 4 shown. It can be seen from Figure 4 that the phosphorescence growth process could be seen during the 1-minute irradiation with the ultraviolet lamp. Figure 4 It can be seen that white stripes gradually covered the thin film under the irradiation of the ultraviolet lamp, that is, the phosphorescence growth process. When the white stripes covered the thin film, the phosphorescence intensity was the strongest and the lifetime was the longest.

[0081] Figure 5 This is the cyclic experiment of the thin film obtained in Example 1 under the room-temperature atmospheric environment under the excitation of a 254 nm ultraviolet lamp. It can be seen from Figure 5 that the prepared thin film can be recycled multiple times and its performance can still be maintained unchanged (the phosphorescence intensity still remains at the same level).

[0082] Figure 6 This is the phosphorescence spectrum of the thin film obtained in Example 1 before and after being irradiated with a 254 nm ultraviolet lamp for 1 minute under the room-temperature atmospheric environment; Figure 7 This is the phosphorescence lifetime decay curve of the thin film obtained in Example 1 before and after being irradiated with a 254 nm ultraviolet lamp for 1 minute under the room-temperature atmospheric environment; It can be seen from Figure 6 andFigure 7 It can be seen that the phosphorescence emission peak of the film is at 488 nm, and the phosphorescence lifetime at 488 nm increases from 37.08 ms to 1415.41 ms. It can be seen that after 1 minute of ultraviolet irradiation, white stripes cover the film, making the phosphorescence grow to the highest intensity and the lifetime reach the best.

[0083] Figure 8 This is the phosphorescence photograph of the film obtained in Example 1 under room temperature and atmospheric environment after 1 minute of irradiation with a 254 nm ultraviolet lamp; Figure 8 It can be known that, relative to the PVA matrix, Example 1 prepared with PVA-co-27%PE as the matrix has excellent RTP performance. (At present, the PVA matrix is the most widely used polymer matrix)

[0084] Under room temperature and atmospheric environment, the phosphorescence emission spectrum and the phosphorescence lifetime decay curve of the film obtained in Example 2 before and after 1 minute of irradiation with a 254 nm ultraviolet lamp at room temperature and atmospheric environment were taken (as Figure 9 shown). Figure 9 It can be known that the phosphorescence emission peak of the film is at 488 nm, and the phosphorescence lifetime at 488 nm increases from 21.62 ms to 1387.83 ms. It can be seen that Example 2 has good phosphorescence performance similar to that of Example 1.

[0085] Under room temperature and atmospheric environment, the phosphorescence emission spectrum and the phosphorescence lifetime decay curve of the film obtained in Example 3 before and after 1 minute of irradiation with a 254 nm ultraviolet lamp at room temperature and atmospheric environment were taken (as Figure 10 shown). Figure 10 It can be known that the phosphorescence emission peak of the film is at 488 nm, and the phosphorescence lifetime at 488 nm increases from 9.89 ms to 1377.41 ms. It can be seen that Example 3 also has good phosphorescence performance similar to that of Example 1, indicating the availability and universality of this strategy.

[0086] Figure 11 This is the afterglow photograph of the films obtained in Example 2 and Example 3 under room temperature and atmospheric environment after 1 minute of irradiation with a 254 nm ultraviolet lamp. Figure 11 It can be seen that white stripes cover the transparent film based on poly(vinyl alcohol-co-ethylene), and there is an obvious afterglow phenomenon; in addition, with the increase of hydroxyl groups, the phosphorescence growth of the film is more obvious and the afterglow time is longer.

[0087] In summary, the present invention functionalizes a general small-molecule chromophore and then physically dopes it with poly(vinyl alcohol-co-ethylene). The obtained host-guest doped long afterglow material exhibits long-lived blue-green phosphorescence after excitation by a 254 nm ultraviolet lamp. More importantly, the phosphorescence intensity of the film has an obvious ultraviolet-driven growth characteristic, and the phosphorescence reaches the strongest when the irradiation time is 1 minute. The preparation method of the film material is simple in operation and low in production cost, providing a new strategy for designing host-guest doped long-lived room-temperature phosphorescence materials, and having good application prospects in the fields of environmental protection and green encryption in the atmospheric environment and the like.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Those of ordinary skill in the art should understand that any modifications or equivalent replacements made to the technical solutions of the present invention without departing from the purpose and scope of the present technical solution shall be covered by the scope of the claims of the present invention.

Claims

1. A phosphor, characterized in that, It has the following structural formula:

2. The phosphor according to claim 1, wherein It is obtained by adopting the following preparation process: 1) Dissolve 4'-hydroxy-[1,1'-biphenyl]-4-carbaldehyde in tetrahydrofuran, add potassium carbonate, and stir evenly for 0.5 h under an inert atmosphere at 65 °C; 2) Dissolve chlorotriphosphazene in tetrahydrofuran; 3) Dropwise add the solution obtained in step 2) into the solution obtained in step 1), react fully at 70 °C for 12 h, then cool to room temperature, remove tetrahydrofuran, and the obtained residue is purified to obtain a pale yellow product, which is the phosphor.

3. The phosphor according to claim 2, wherein The molar ratio of the 4'-hydroxy-[1,1'-biphenyl]-4-carbaldehyde to the chlorotriphosphazene is 6:

1.

4. A long-lived room temperature phosphorescent material driven by light for phosphorescence growth, characterized in that, It includes the phosphor according to any one of claims 1 to 3.

5. The long-lived room temperature phosphorescent material for photo-driven phosphorescence growth according to claim 4, wherein Its preparation method includes the following steps: Mix the phosphor and the polymer matrix in a ratio of (0.1-3) mg: 1 ml, stir evenly, and then drop the obtained mixed solution on a glass slide to form a transparent film, thus obtaining a long-lived room temperature phosphorescent material; wherein, the polymer matrix is a dimethyl sulfoxide solution of poly(vinyl alcohol-co-ethylene).

6. The long-lived room temperature phosphorescent material for photo-driven phosphorescence growth according to claim 5, wherein The mass percentage content of ethylene in the poly(vinyl alcohol-co-ethylene) is 27-38%.

7. Application of a long - lifespan room - temperature phosphorescent material, characterized in that, Use the long-lived room temperature phosphorescent material according to any one of claims 4 to 6 in the fields of information transmission and destruction, and dynamic green anti-counterfeiting.

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